My reference image won't show!
Reference images are visible when you are in orthographic top, down, back, front, right or left view. The shortkeys are, respectively: Numpad 7, CtrlNumpad 7, Numpad 1, CtrlNumpad 1, Numpad 3 or CtrlNumpad 3. And also in camera view Numpad 0, with thanks to cegaton :)